title: A terminal energy acceptor of the phycobilisome: the 75,000-dalton polypeptide of Synechococcus 6301 phycobilisomes--a new biliprotein.
abstract: A rapid procedure is described for the isolation of "linker" polypeptides (Lundell, D. J., R. C. Williams, and A. N. Glazer. 1981. J. Biol. Chem. 256:3580-3592) of cyanobacterial phycobilisomes. The 75,000-dalton component of the core of Synechococcus 6301 phycobilisomes isolated by this procedure has been shown to carry a bilin similar in spectroscopic properties to phycocyanobilin. "Renatured" 75,000-dalton polypeptide has absorption maxima at 610 and 665 nm and a fluorescence emission maximum at 676 nm, similar to that of intact phycobilisomes. A complex of allophycocyanin and a 40,000-dalton bilin-carrying fragment of the 75,000-dalton polypeptide, obtained by limited tryptic digestion, is described. This complex, which lacks allophycocyanin B, shows a fluorescence emission maximum at 676 nm. The above data indicate that the 75,000-dalton polypeptide functions as a terminal energy acceptor in the phycobilisome.
mesh_terms: D000458:Cyanobacteria / Q000502:physiology*; D004579:Electron Transport; D045342:Light-Harvesting Protein Complexes; D008970:Molecular Weight; D010788:Photosynthesis; D045524:Phycobilisomes; D010940:Plant Proteins / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
chemical_list: D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D010940:Plant Proteins